Fabrication, characterization and magnetic behaviour of alumina-doped zinc ferrite nano-particles

Zinc ferrite nano-powders with a nominal composition of ZnFe2O4 were prepared by combustion synthesis using mixture of urea and ammonium nitrate as fuel. The influence of alumina-doping on the structural, morphological and magnetic properties of ZnFe2O4 nano-particles was investigated by means of X-ray powder diffraction (XRD), infrared (IR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and vibrating sample magnetometer (VSM). XRD and IR analyses confirm the cubic spinel phase of ZnFe2O4 nano-particles. The Zn ferrite presented a uniform microstructure with grain size in nano-scale. Alumina-doping brought about a change in the morphology of the as prepared ferrite from sphere-like to regular hexagon. Al2O3-treatment led to a decrease in the coercivity (Hc), magnetization (Ms) and magnetic moment (nB) of the investigated system. The maximum decrease in the values of Hc, Ms and nB due to the treatment with 1.5 wt% Al2O3 attained 13.5, 17.4 and 13.5%, respectively. The observed results can be explained on the basis of particle size and the Fe3+ concentration in the octahedral and tetrahedral sites involved in the cubic spinel structure.